Abstract
Water must condense into ice clouds in the coldest brown dwarfs and exoplanets. When they form, these icy clouds change the emergent spectra, temperature structure, and albedo of the substellar atmosphere. The properties of clouds are governed by complex microphysics but these complexities are often not captured by the simpler parameterized cloud models used in climate models or retrieval models. To accurately interpret the exquisite details JWST observations show of ultra-cool substellar objects, we need to be prepared to efficiently generate atmospheric models without compromising the accuracy of the cloud’s morphology and optical properties, both of which significantly impact the observables. In this talk, I will discuss how we combine microphysical cloud modeling and 1D climate modeling with the goal of incorporating insights from microphysical models into a self-consistent, parameterized cloud model. Additionally, I will highlight the differences in the observables between the current water cloud prescription and those with our new microphysically informed water clouds. The improvements discussed here will be used towards analyzing JWST observations of ultra-cool substellar worlds including WISE 0855, the coldest known brown dwarf. Finally, I will introduce the initial development of the fifth iteration of Sonora models, an expansion upon the existing suite to encompass much colder temperatures, clear and cloudy atmospheres, and chemical disequilibrium across a broad range of metallicities, and C/O ratios. These new atmosphere models will be included as boundary conditions for the first substellar evolution models that include volatile clouds in addition to more refractory clouds at higher temperatures.
